Genetically modified organisms (GMOs), in particular genetically modified plants, are gaining importance in agriculture as well as in the production and marketing of foods and feed.
However, due to existing concerns regarding the impact of GMOs on the environment and on consumers' health, the introduction of new GMOs commonly requires regulatory approval and, in many countries including the European Union, food and feed products containing or produced from GMOs are themselves subjected to authorisation and compulsory labelling (see, e.g., Regulation (EC) no. 1829/2003. Off J Eur Communities: Legis. 2003, L268: 1-23; Regulation (EC) no. 1830/2003. Off J Eur Communities: Legis. 2003, L268: 24-28).
Consequently, tracing of GMOs in the environment and through the cultivation process and the food or feed production chain is fundamental for environmental risk assessment, as well as necessary to preserve consumers' confidence and to satisfy or verify the observance of mandatory regulations, including GMO product labelling.
This requires the availability of methods that can determine the presence, identity and/or quantity of GMOs or materials originating or derived therefrom in, for example, food and feed sources, ingredients and/or processed consumables. DNA-based methods are very useful in this respect, not least because DNA often withstands physical and chemical food processing treatments better than other molecules, such as proteins. For example, real-time polymerase chain reaction (PCR) proved to be a specific and sensitive technique for the quantification of nucleic acids indicative of the presence of DNA originating from GMOs.
Assays are available to unambiguously conclude the presence or absence of genetic material derived from a select plant transformation event in a sample. Commonly, such assays can detect the presence of a unique, event-specific nucleotide sequence found in the plant transformation event of interest but absent from other events. For example, such distinctive nucleotide sequences may be present at junctions between the GMO's endogenous genomic sequence and the sequence of the transforming gene construct at the genomic insertion site of the latter; detection may for instance involve PCR amplification across the said junction using specific primers flanking the junction (see, e.g., Hernandez et al. 2003. Transgenic Res 12: 179-189; Hernandez et al. 2004. J Cereal Sci 39: 99-107; Berdal et al. 2001. Eur Food Res Technol 213: 432-438; Nielsen et al. 2004. Eur Food Res Technol 219: 421-427; or Ronning et al. 2003. Eur Food Res Technol 216: 347-354).
However, these event-specific assays can often be procured only as highly priced kits allowing for a limited number of tests, are confined to detection of material from a single event, and commonly employ very particular reaction conditions. Yet, the number of generated, authorised and marketed and GMOs keeps increasing. Hence, an unambiguous determination of the GMO composition of a sample would in principle require to apply an ever-growing battery of separate event-specific detection assays on each sample, which is both laborious and cost demanding.
Therefore, while it continues to be desirable to employ event-specific assays due to the unambiguous nature of their output, there exists a need for using these assays in a more effective and targeted manner, such as to improve the detection of GMOs detection, e.g., in terms of time expense, cost and labour intensity.